Abstract: A method and apparatus of tracing VP's (virtual paths) wherein operational information of VP connectors are collected through OAM (operation and maintenance) cells. The VP connectors establish a connection at a VP level within a network in which the cells are transferred in an ATM (asynchronous transfer mode). Each VP connector detects an OAM cell for VP tracing as received from another of the VP connectors, and judges if an area for affixing the operational information in the VP connector itself exists in the detected OAM cell. In the VP connector when the area exists, the detected OAM cell is specified to be the OAM cell for writing the operational information thereinto, and the specified OAM cell is sent out after affixing the operational information thereto.

Abstract: In a test method and apparatus for testing a virtual path in an asynchronous transfer mode system, a sequence number is included in an operation administrating monitoring (OAM) cell to specify the OAM cell for testing a virtual path between transmission and reception sides. The sequence number is inserted into the OAM cell by the use of an idle cell and is received by a sequence number test circuit included in the reception side. The sequence number in the OAM is collated with a result of counting the OAM cell in the reception side to detect coincidence or non-coincidence between the sequence number and the result of counting. On detecting the non-coincidence, a loss of the OAM cell or wrong reception of the OAM cell is detected on the reception side. Otherwise normal operation is confirmed between the transmission and the reception sides.

Abstract: Virtual path operation information of each of the stations of an synchronous transfer mode telecommunications network is traced using OAM cells. OAM cells used for operation and maintenance control of the asynchronous transfer mode telecommunication network have a pointer indicative of the position where virtual path operation information is recorded and an area for storing virtual path operation information of a certain number of stations. Each station records virtual path operation information in an OAM cell, updates the pointer and sends the OAM cell to the next station on a selected path. When the payload of the OAM cell becomes full, the OAM cell records new OAM cell generation request information and the pointer is changed to the final value and is sent to the next station.